I finally had time to play both Auras in my possession. Both were bought second-hand, both from Ebay, though I got the first one in October and the second just about a month ago. I tried both with the same few reeds and the same Selmer 404 ligature.
Bear in mind that terms like "bright" and "dark" have become so subjective in my mind that I don't even feel like I know what they mean any more. That being said:
The first one as I said above compares very favorably to my EB Link STM, which was worked on and opened to about .108" by Erik G. The Aura is if anything slightly easier to play, especially in the low register. I use these two 'pieces almost interchangeably, both with Selmer 404 ligature and Vandorn V16 2.5. I would say both of these are on the mid-to-brighter side of Link tone, with lots of overtones. Neither seems thin to me (or I'd get rid of 'em) but have a big, powerful sound.
The second mouthpiece is distinctly different, but not a lot different. In terms of playability it seems about the same from top to bottom of the horn. The tone though is a bit "darker" (here we go) - fewer overtones, and more focused. I don't hear it as louder or softer, just different. It reminds me a little more of a bronze Berg I have but I think this Aura is still on the Link spectrum, so to speak. It does fit slightly tighter on the neck cork of my horn, which I find weird. Not to the point of being difficult or compressing the cork but it's definitely a tighter shank than the first one.
One caveat - I now have 4-5 mouthpieces I use in an irregular rotation. I primarily play with a 10-piece horn-rock group and I need a lot of cut, but without being bright and obnoxious. I go from the EB Link to the first Aura to the Berg to a heavily modified Yanigisawa metal piece I picked up not long ago. I use V16s with some, Rico orange box with others. It doesn't seem to matter which one I put on the horn, after 10-15 minutes I just sound like "myself" again.
One more caveat - I've tried dozens of mouthpieces in the last 10 or so years. Some were bargains found here or Ebay, some were high-dollar recent offerings (Wanne, Barone, etc). I don't consider myself a great player by any means, nor an authority on the subject. Mouthpieces seem to fall into three categories for me. 1 - those that resemble my Link, 2 - those that sound more like the Berg, and 3 - those that I either hate the sound, the playability, or both.
No idea if this'll help anyone, but there you have it. I'm torn between keeping the new Aura or moving it on. It sounds and plays like a thing or two I already have, but it also was so inexpensive that selling it might not be worth the effort. Decisions, decisions...
I will say this: now having sampled two of them, my opinion is that the variation between examples is no worse than with any other modern mouthpiece maker and a hell of a lot less than many. I'd be happy with either of these and I still wouldn't hesitate to recommend an Aura to just about anybody.